The word yoga comes from the Sanskrit word "yuj" means to unite. I'd like to mention, Yoga/Yog belongs to Santana Dharma. All hindu people practices yoga; hinduism does not exist without yoga and vice versa. It is open to all who wish to practice it. Being able to do yoga postures has to be the side effect of practicing yoga because the main goal of yoga is to let one realise his/her own innate, pure and eternal nature of the self.
Asana means ‘the seat’. When the series of different asanas is sequenced together is called yogasanas. Asana and Pranayama is like a base step of a ladder though independent, works together to exercise the anterior, posterior, lateral and interior portions of body equally bringing total attention to endure all five sheaths of the body. We have 5 different layers from the outer most layer to the inner most layer (the anatomical body, Physiological body, The mental body, the intellectual body and the Spiritual body). Yogasanas are psycho-physiological unlike physical exercises, which are purely external. Asana develops body awareness; generate internal consciousness and stabilizes the mind.
The Practice of yoga brings a perfect balance in body and mind, developing steadiness, composure and firmness.